R-134 A/C conversion questions
 

I replaced all the o-rings, drained old oil out of compressor. On an 86 944 are the 2 valves on the hard lines on top, the high and low side the only 2 that need the adaptor valves? I guess the valve on the compressor would be for the pressure gauge hookup and will it need any adaptor? I plan on taking it to have it evacuated and charged with new oil and R-134 and just wanted everything hooked up before I went there.
Thanks,
Todd

Technically you only need an adapter on the low-side port, since that's where all your filling and pressure readings are done.

The high-side one that came with my conversion kit didn't even fit, so I just changed the low one, filled it and have been living happily ever after.

Hey Todd, sounds like you went to a lot more work than necessary. Not sure why you drained the oil, but since you opened it up that much I hope you replaced the dryer as well. You should replace the valve on both lines if possible so you can hook gauges to both sides in case of the system not cooling. You will need both readings when troubleshooting a nonworking system. If you can't.... then do as Jeff did and change the low side. I THINK (but I'll have to check when I get home) that the valve on the fender is a high side...like I said though, I'll have to check when I get home. The way to tell is the line coming from the firewall to the compressor is the low side line.

A/C
 

Forgot to mention that I did change the dryer. I changed out the compressor because the one on it had a little oil around the clutch and there was no pressure in the system, so I imagine the compressor was leaking. I just wanted all new o-rings that were compatable with the R-134. I have a valve on both line on the fender well along with one on the compressor. I figured the valve on the compressor was where the vacumm gauge would connect and the the other 2 valves on the fender well were for the high and lwo side.
Todd

when converting to r134, you need to drain the oil dont you?

As far as I know, the minimum that needs to be done is drained compressor, new receiver/dryer, new o-rings, evacuated, new oil and R-134
Todd

The fat hose is always the low/ suction side. Draining the oil? Depends on who you ask. Outside of that, replace the o-rings where you disconnect lines. Todd, are you going to replace the expansion valve?

You don't have to drain the oil...just make sure the two are compatible (don't use PAG oil as it is not compatible with the original type oil). The oil is spread throughout the whole system and not just in the compressor so you can't drain the oil anyway unless you remove all the parts and clean them. Flushing the system will help and changing the dryer will help even more but there is still quite a bit in the condensor and evaporator.

It's always best to drain the compressor oil out so you have a baseline for charging. I recommend using the r134a cannisters that have ester oil pre-loaded in the proper proportion into them already. Far less chance of stuff getting screwed up that way.

I have a place that services A/C and they can add the correct amount of oil after they evacuate and check for leaks before they add the R-134. I did this on an 85 RX-7 and it pulled down to 40 degrees whcih I thought was great. Hopefully I can get the same results on the 944. Thanks for all the info.
Todd